I don't agree at all. The reasons in the article all seem like "envs are bad because if you make a mistake you can expose them". This is not exclusive to envs, it applies to all secrets, independent of the medium used to make it available to the process using it.
In my experience, if you prevent using envs for secrets (as docker swarm does) all you get is a disgruntled programmer reading the contents of a secret file to an env in the entrypoint.
In my experience, if you prevent using envs for secrets (as docker swarm does) all you get is a disgruntled programmer reading the contents of a secret file to an env in the entrypoint.